Conventionally, mattress innerspring structures comprise a plurality of coil springs which are positioned adjacent one another to extend between top and bottom face surfaces of a mattress. The individual coil springs or coils are held together by various means to form a unitary innerspring structure.
The coils in the innerspring structure are typically formed very similar to each other, having generally the same coil diameter and stiffness. Therefore, the top surface of a typical mattress will have generally equal firmness throughout the mattress. However, it is often desirable to make certain areas on the mattress more firm than other areas of the mattress. For example, it may be desirable to firm up the center section of the mattress which receives a majority of the weight from a person lying thereon. Further, it may be desirable to make the edge of a mattress more firm or durable to withstand pressures created when people sit on the end of their bed.
Therefore, it is an objective of the present invention to increase the firmness in selected areas of a mattress.
It is a further objective to increase the durability of selected areas on a mattress which receive a high amount of loading during normal usage.
Accordingly, it is another objective of the invention to provide an innerspring structure which is more firm and provides greater support in certain areas thereon than in other areas.
Furthermore, it is an objective of the invention to provide such an innerspring structure at a relatively low cost and with a relatively uncomplicated design.